[pocket-linux] Libc.so.6 problems in Chapter 3: Maybe a solution

[Benoît Depaire]

On 6/6/05, David Horton <dhorton at speakeasy.net> wrote:
> Benoît Depaire wrote:
> > Hi everybody,
> >
> > I've been working with the pocket linux guide for a couple of weeks
> > now, and have been stuck lately at chapter 3. I got the well known
> > boot problem with the c library (the shared library was not found).
> >
> > I've been looking for a solution, reading the previous mails on this
> > mailing list. Ofcourse, I could have just passed this problem and go
> > on with chapter 4 (using the available images), but I wanted to
> > understand why my approach was failing.  After quite some testing, I
> > might have an idea what the problem is and decided that I know enough
> > now to proceed. However, not sure if my solution will or if I found
> > the real reason for the problem (I am planning to check this in the
> > future), I still want to share my thoughts with the rest.
> >
> > In another conversation on this topic, David Horton mentioned the
> > possible problem was the fact that the used c library was build for a
> > i686 and it was used on a i386 machine. However, another person (sorry
> > forgot the name, and too lazy to look it up), mentioned the disks
> > didn't work either on the original machine used to build the disks
> > (and from which libc was taken).
> >
> > However, I suspect that the problem is somewhere in the same line. I
> > suspect that the library is not "found" because it was build against a
> > different kernel than that used on the bootdisk. Let me tell you why I
> > think so:
> >
> > I created a new partition on my laptop (which i use to build the
> > boot/root disks) and copied the rootdisk to this partition. Next I
> > copied the vmlinuz (for i386 machine, taken from the bootdisk image
> > available at the pocket linux website) to the boot directory, where
> > the other kernels of this machine are located. Finally, I added a new
> > entry in the lilo.conf file. When rebooting the machine, choosing to
> > load the pocket linux kernel, it failed exactly the same way as on the
> > machine I use the disks on. Thus, the type of machine (laptop =
> > pentium M 1500mhz, other machine = desktop= pentium II 233 i believe)
> > can not be the reason.
> >
> > Next I changed the pocket linux kernel in my boot directory with the
> > original kernel working on this laptop. Now, the booting process looks
> > pretty much the same, but now the bash shell shows up. Therefore, I
> > believe the problem has something to do with the kernel-libc
> > combination.
> >
> > Another indication is a certain parameter, that can be set during the
> > compilation of glibc.
> >
> > `--enable-kernel=version'
> >     This option is currently only useful on Linux systems. The version
> > parameter should have the form X.Y.Z and describes the smallest
> > version of the Linux kernel the generated library is expected to
> > support. The higher the version number is, the less compatibility code
> > is added, and the faster the code gets. '
> >
> > Now, you must now that I'm running a Mandrake 10.0 distro, so I can
> > easily believe that my c library is optimized for my kernel and fails
> > to work with older kernels, which i believe the kernel on the boot
> > disk image clearly is.
> >
> > To be sure this is the real cause, one should compile the gnu c
> > libraries (glibc) for the older kernel and see if that works. However,
> > because compiling the gnu c libraries for another system than the host
> > system, seems rather complicated, I postpone this thill after the
> > pocket linux experience :).
> >
> > Finally I would like to mention that the program library how-to on the
> > linux documentation project was a great help in understanding how the
> > libraries work. I could recommend this reading to anybody who wants to
> > know how linux finds the shared libraries.
> >
> > Cheers,
> > Benoît
> >
> > PS: An idea i had lately, maybe interesting as addition to the pocket
> > linux guide. Maybe it's possible to use the gmailfs (gmail account as
> > file system) together with pocket linux
> >
> > _______________________________________________
> > Pocket-Linux mailing list
> > Pocket-Linux at ufo.chicago.il.us
> > http://ufo.chicago.il.us/cgi-bin/mailman/listinfo/pocket-linux
> 
> 
> I think your advice about kernel-libc versions is very good.  The
> "--enable-kernel=version" may very well be the key.  It seems logical
> that distro makers might choose speed over compatibility when compiling
> glibc.
> 
> By the way, what version of kernel source are you using compared to the
> kernel supplied with Mandrake?  Are they drasticly different?  For
> example, 2.4 vs. 2.6 or is it just a minor difference?
> 
> Dave
> 
> 
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> 

The mandrake kernel is 2.6.3-7 (for i686). The other kernel (which
works) is the one on the bootdisk image supplied at
pocket-linux.sourceforge.net. I don't know what version that is. I
can't simply copy uname to the rootdisk, because it needs a higher
version of libc, than the one from the working rootdisk image. But I
hope you have an idea what version of kernel there is on the bootdisk?

Benoît